1. Field of Invention
The present invention relates to a surface treatment method, and particularly to a surface treatment method of a magnesium alloy article and a structure thereof, which are applicable in a hairline finish process.
2. Related Art
Currently, a casing of an electronic product such as notebook computer, mobile phone, and personal digital assistant (PDA) is mostly made of a plastic material, which has poor visual aesthetics and contact sense. Therefore, casings of the electronic devices made of metal materials are used by some manufacturers, such that metal texture is generated on the appearance of the product, and the aesthetics and contact sense are improved.
With a notebook computer as an example, in order to meet the demands of light, thin, high strength, and good heat dissipation, the casing of the notebook computer is generally made of light metal materials such as magnesium (Mg) alloy, aluminum (Al) alloy, magnesium-aluminum (Mg—Al) alloy, titanium (Ti) alloy, and magnesium-titanium (Mg—Li) alloy. The light metals are molded into the casing of the computer generally by compression molding and injection molding, which is combined with subsequent surface treatment process such as coating and baking, plating, and anode processing, to fabricate a metal casing having desired appearance texture.
Among the light metal materials, the magnesium alloy has numerous excellent material properties, is generally accepted as the most potential light weight material, and has been widely used in 3C electronic products. Due to the limitation of the material property of the melted magnesium alloy, poor surface quality of the molded magnesium alloy work piece is caused, so that the appearance texture and the contact sense of the casing of the electronic device are not good. Therefore, after molding, the magnesium alloy work piece further needs to be performed with some subsequent processes such as hole puttying, grinding, and polishing, and thus time and labor are consumed, and the original metal color texture cannot be directly exhibited.
In order to eliminate the limitation of the magnesium alloy material, an improved process is developed at present. According to a conventional improved process, the magnesium alloy work piece after molding must be puttied, and a layer of primer is sprayed on the surface of the magnesium alloy work piece. Only after the repair process step, a hairline finish processing is performed on the surface of the magnesium alloy work piece clad with the primer, and then a coating layer having metal ingredients such as nano lacquer is coated on the surface of the magnesium alloy work piece after the hairline finish processing, such that the surface of the magnesium alloy work piece will exhibit a metal texture and color.
Although the conventional surface treatment process addresses the problem that the appearance of the magnesium alloy work piece must have metal texture, as a layer of primer is clad on the surface of the magnesium alloy work piece in advance, the hairline finish processing is practically performed on the primer, instead of the magnesium alloy work piece itself. Moreover, after the hairline finish processing, multiple polishing processing procedures such as coating of nano lacquer must be performed, thus resulting in limitations such as too complicated magnesium alloy surface treatment procedures and too high manufacturing cost.